package com.hmdp.service.impl;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.CacheClient;
import com.hmdp.utils.RedisConstants;
import com.hmdp.utils.RedisData;
import com.hmdp.utils.SystemConstants;
import org.springframework.data.geo.Distance;
import org.springframework.data.geo.GeoResult;
import org.springframework.data.geo.GeoResults;
import org.springframework.data.redis.connection.RedisGeoCommands;
import org.springframework.data.redis.domain.geo.GeoReference;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import org.springframework.data.redis.core.StringRedisTemplate;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;


import javax.annotation.Resource;

import java.time.LocalDateTime;
import java.util.*;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import static com.hmdp.utils.RedisConstants.*;


/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {
    @Resource
    private CacheClient cacheClient;

@Resource
private StringRedisTemplate stringRedisTemplate;
    @Override
    public Result queryById(Long id) {
        //缓存穿透问题
        //Shop shop = queryWithPassThrough(id);
        // 互斥锁解决缓存击穿
         Shop shop = cacheClient
                .queryWithMutex(CACHE_SHOP_KEY, id, Shop.class, this::getById, CACHE_SHOP_TTL, TimeUnit.MINUTES);
     if(shop==null){
        return Result.fail("商户不存在");
    }
       //Shop shop = queryWithLogicalExpire(id);
        return Result.ok(shop);


    }
    //逻辑过期缓存
    private static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);
    public Shop queryWithLogicalExpire( Long id ) {

        String key = CACHE_SHOP_KEY + id;
        // 1.从redis查询商铺缓存
        String json = stringRedisTemplate.opsForValue().get(key);
        // 2.判断是否存在
        if (StrUtil.isBlank(json)) {
            // 3.存在，直接返回
            return null;
        }
        // 4.命中，需要先把json反序列化为对象
        RedisData redisData = JSONUtil.toBean(json, RedisData.class);
        Shop shop = JSONUtil.toBean((JSONObject) redisData.getData(), Shop.class);
        LocalDateTime expireTime = redisData.getExpireTime();
        // 5.判断是否过期
        if(expireTime.isAfter(LocalDateTime.now())) {
            // 5.1.未过期，直接返回店铺信息
            return shop;
        }
        // 5.2.已过期，需要缓存重建
        // 6.缓存重建
        // 6.1.获取互斥锁
        String lockKey = LOCK_SHOP_KEY + id;
        boolean isLock = tryLock(lockKey);
        // 6.2.判断是否获取锁成功
        if (isLock){
            CACHE_REBUILD_EXECUTOR.submit( ()->{
        //这里我们使用try进行包裹  确保释放锁一定成功
                try{
                    //重建缓存
                    this.saveShop2Redis(id,20L);
                }catch (Exception e){
                    throw new RuntimeException(e);
                }finally {
                    //释放锁
                     unLock(lockKey);
                }
            });
        }
        // 6.4.返回过期的商铺信息
        return shop;
    }

    private void saveShop2Redis(Long id, long  expireSeconds) {
        //查询店铺数据
        Shop shop = getById(id);
        //封装逻辑过期时间
        RedisData redisData = new RedisData();
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireSeconds));
        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY + id,JSONUtil.toJsonStr(redisData));

    }

    //互斥锁缓存击穿问题方法

    public Shop queryWithMutex(Long id) {


            //1.从redis中查询商户信息
            String key= CACHE_SHOP_KEY+id;
            String shopJson = stringRedisTemplate.opsForValue().get(key);
            //2,存在，直接返回
            if(StrUtil.isNotBlank(shopJson)){

                return JSONUtil.toBean(shopJson, Shop.class);
            }
            //判断命中的是否为空值
            if(shopJson != null){
                return  null;
            }
            //缓存重建
            //获取锁
        String lockKey = "lock:shop:" + id;
        Shop shop = null;
         try{   boolean islock = tryLock(lockKey);
            //判断是否获取锁成功
            if(!islock){
                //获取失败，获取锁失败，休眠10秒，并尝试获取锁
                Thread.sleep(50);
                return queryWithMutex(id);
            }
            //获取锁成功，根据id查询数据库
            //3.不存在，根据id查询数据库
            shop = getById(id);
            if(shop==null){
                //设置一个空值对象
                stringRedisTemplate.opsForValue().set(key,"" ,RedisConstants.CACHE_NULL_TTL,TimeUnit.MINUTES);
                return null;
            }
            stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(shop));
            //设置缓存时间
            stringRedisTemplate.expire(key, CACHE_SHOP_TTL, TimeUnit.MINUTES);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        }finally {
            //释放锁
            unLock(lockKey);
        }

        //返回
        return  shop;
    }
    //缓存穿透问题方法
    public Shop queryWithPassThrough(Long id) {
        //1.从redis中查询商户信息
        String key= CACHE_SHOP_KEY+id;
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2,存在，直接返回
        if(StrUtil.isNotBlank(shopJson)){

            return JSONUtil.toBean(shopJson, Shop.class);
        }
        //判断命中的是否为空值
        if(shopJson != null){
            return  null;
        }
        //3.不存在，根据id查询数据库
        Shop shop = getById(id);
        if(shop==null){
            //设置一个空值对象
            stringRedisTemplate.opsForValue().set(key,"" ,RedisConstants.CACHE_NULL_TTL,TimeUnit.MINUTES);
            return null;
        }
        stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(shop));
        //设置缓存时间
        stringRedisTemplate.expire(key, CACHE_SHOP_TTL, TimeUnit.MINUTES);
        return  shop;
    }
    //获取锁
    private boolean tryLock(String key){
        boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }
    //释放锁
    private void unLock(String key){
        stringRedisTemplate.delete(key);
    }

    @Override
    @Transactional
    public Result update(Shop shop) {
       Long id = shop.getId();
        if(id== null){
            return Result.fail("商户不存在");
        }
        //1.更新数据库
        updateById(shop);
        //2.删除缓存
        stringRedisTemplate.delete(CACHE_SHOP_KEY+id);

        return  Result.ok();
    }

    @Override
    public Result queryShopByType(Integer typeId, Integer current, Double x, Double y) {
        // 1.判断是否需要根据坐标查询
        if (x == null || y == null) {
            // 不需要坐标查询，按数据库查询
            Page<Shop> page = query()
                    .eq("type_id", typeId)
                    .page(new Page<>(current, SystemConstants.DEFAULT_PAGE_SIZE));
            // 返回数据
            return Result.ok(page.getRecords());
        }

        // 2.计算分页参数
        int from = (current - 1) * SystemConstants.DEFAULT_PAGE_SIZE;
        int end = current * SystemConstants.DEFAULT_PAGE_SIZE;

        // 3.查询redis、按照距离排序、分页。结果：shopId、distance
        String key = SHOP_GEO_KEY + typeId;
        GeoResults<RedisGeoCommands.GeoLocation<String>> results = stringRedisTemplate.opsForGeo() // GEOSEARCH key BYLONLAT x y BYRADIUS 10 WITHDISTANCE
                .search(
                        key,
                        GeoReference.fromCoordinate(x, y),
                        new Distance(5000),
                        RedisGeoCommands.GeoSearchCommandArgs.newGeoSearchArgs().includeDistance().limit(end)
                );
        // 4.解析出id
        if (results == null) {
            return Result.ok(Collections.emptyList());
        }
        List<GeoResult<RedisGeoCommands.GeoLocation<String>>> list = results.getContent();
        if (list.size() <= from) {
            // 没有下一页了，结束
            return Result.ok(Collections.emptyList());
        }
        // 4.1.截取 from ~ end的部分
        List<Long> ids = new ArrayList<>(list.size());
        Map<String, Distance> distanceMap = new HashMap<>(list.size());
        list.stream().skip(from).forEach(result -> {
            // 4.2.获取店铺id
            String shopIdStr = result.getContent().getName();
            ids.add(Long.valueOf(shopIdStr));
            // 4.3.获取距离
            Distance distance = result.getDistance();
            distanceMap.put(shopIdStr, distance);
        });
        // 5.根据id查询Shop
        String idStr = StrUtil.join(",", ids);
        List<Shop> shops = query().in("id", ids).last("ORDER BY FIELD(id," + idStr + ")").list();
        for (Shop shop : shops) {
            shop.setDistance(distanceMap.get(shop.getId().toString()).getValue());
        }
        // 6.返回
        return Result.ok(shops);

    }


}
